Inoculant injector instrument



Aug. 3l, 1954 F. zlHERL ETAL 2,687,724

INOCULANT INJECTOR INSTRUMENT Filed March 2. 1950 3 Sheets-Sheet l 1. 1 F\ G. E5

u INVENToRs Fmi FRANK ZmeRL By ARTHUR S. me

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ATTORNEY.

Aug. 31, 1954 F. zlHERL. ETAL 2,587,724

INOCULANT INJECTOR INSTRUMENT Filed March 2, 1950 3 Sheets-Sheet 2 y INVENTORS.

FRANK Z mem.

WAR-mun S. KH

www@ M AT TOQNY Aug. 3l, 1954 F. z|HERL Erm.

INOCULANT INJECTOR INSTRUMENT 3 Sheets-Sheet 3 Filed Ilarch 2, 1950 QH .5 Pow @OH n man". m T E O mm .n mZfA um mm FAW n mmm N5 md .Sdi

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Patented Aug. 31, 1954 2,687,724 IN OCULANT INJECTOR INSTRUMENT Frank Ziherl, Euclid, and Arthur S. Kish, Cleveland, Ohio, assignors, by mesne assignments, to Geolrey W. Walker, Frank Ziherl, and Louis A. Ziherl, all of Cleveland, Ohio Application March 2, 1950, Serial No. 147,166

(Cl. 12S-173) 16 Claims. l

The present invention relates generally to ins truments used medically for the purpose of injecting inoculant into patients, and more particularly to an instrument for effecting jet or spray inoculation.

Jet or high-pressure spray inoculation is a recently developed medical technique in which medicinal fluids are injected into the body without breakage of the skin, as contrasted to or distinguished from hypodermic injection in which a hollow needle is caused to penetrate the skin and muscle tissue. The injection is accomplished by forcing a very thin stream of fluid through the skin at high pressure. The fluid jet is about .003 inches in diameter, which is approximately the size of a pore in the human skin, and the high velocity of the jet causes it to pass through the skin and diffuse into the muscle tissues.

It is the primary object of our invention to provide an improved instrument or device for effecting the above-described process oi jet inoculation.

Another object of our invention is to provide an instrument of the character described, in which hydraulic means are employed to energize a spring-pressed plunger.

Still another object of the invention is to provide an instrument of the character described, which is manually operable and which can develop very high pressure.

Another object of our invention is to provide an instrument of the character described, with self-loading means to permit repeated injection of inoculant with a single ampule.

Still another object of our invention is to provide an inoculant injector instrument having improved means for metering the inoculant which is to he ejected.

A further object of our invention is to provide said instrument with improved means for limiting the stroke of the plunger and thereby controlling the volume of inoculant which is ejected.

A still further object of our invention is to provide an instrument of the character described, wherein means are provided to prevent leakage or drip of the inoculant from the ampule after the injection has been completed.

Other objects and advantages of the invention will be apparent during the course of the following description.

In the accompanying drawings, forming a part of this specification, and in which like numerals are employed to designate like parts throughout the same,

Fig. 1 is a front end elevation of an injector instrument embodying the features oi our invention.

Fig. 2 is a longitudinal cross-sectional view taken on line 2 2 of Fig. 1.

Fig. 3 is a cross-sectional view of the barrel of the instrument taken as indicated by line 3 3 of Fig. 2.

Fig. 4 is an enlarged fragmentary cross-sectional view of the valve structure taken on line 4 4 of Fig. 2.

Fig. 5 is an enlarged fragmentary cross-sectional view of the locking device taken as indicated byline 5 5 oi' Fig. 2.

Fig. 6 is an enlarged transverse cross-sectional view of the uid reservoir taken on line 6 8 of Fig. 2.

Fig. 7 is an enlarged longitudinal cross-scctional view of a form of ampule or cartridge which is utilized in connection with the injector instrument.

Fig. 8 is a fragmentary cross-sectional view similar to that of Fig. 2 but showing the cartridge in operative position in the injector device.

Fig. 9 is a side elevation of a modiied form of the inoculant injector device as adapted for multiple shot operation, portions thereof being broken away to show details of the structure.

Fig. 10 is a fragmentary cross-sectional view taken on line I0 Il of Fig. 9.

Fig. 1l is a cross-sectional view taken on line H Ii oi' Fig. 9.

Fig. 12 is an enlarged cross-sectional view ci' the plunger cap assembly shown in Fig. 9.

Referring more particularly to Figs. l to 6 oi' the drawings, the injector instrument is seen to have some resemblance to a pistol in its overall appearance, and has a grip or butt portion I, having ornamental side plates I', a barrel portion 2, and a piston housing 3.

The principal part of the device is a unitary body 4 which may be a casting or formed out of rolled bar stock. The upper portion of the body 4 comprises the barrel 2 and piston housing 3, heretofore referred to, and this upper portion is bored as at 5 to slidably receive a plunger 6. The bore 5 is counterbored to form a shoulder 'I and the counterbore is tapped to receive a threaded follower 8 which serves to compress a resilient sealing ring 9 against the shoulder l and thus seal the plunger against leakage.

The bore 5 is additionally counterbored, as viewed from the right of Fig. 2, to form a relatively large compression chamber or cylinder I 0 which slidably receives a piston I I which is secured to or formed integrally with one end of the cess I2 in which is retained a resilient sealing ring I3 which has wiping engagement with the wall of the cavity III.

The open end of cylinder III is closed by means of a cap I4, which is threadedly secured to the exterior of the piston housing 3. The cap is provided with a central aperture to permit the passage therethroughof an extension rod Iyoneend` of which iskthneadedly secured to the piston II. The major portion of the rod I5, which projects or extends beyond the cap I4, is externally threadedly secured and a lock nut IB The forepart or barrel portion 2. of the body 4 is bored as at 20 and internally threaded t'o receive a self-opening collet 2| having a series of longitudinal slots 22 therein which permit the jaws 23 `thereof to be converged or contracted into gripping or clamping relationship. The inner face of the jaws 23 has formed thereon an annular groove or recess 24 which, as will more fully appear hereinafter, is adapted to embrace a cartridge C, described hereinafter. The plunger 6, which has an undercut or clearance portion 25, is slidable Within the collet 2 I.

The bore 23 is counterbored at 23 forming an annular recess which 21.y A tubular sleeve 2B which surrounds the collet 2l is slidably received in the annular recess. The sleeve 28 terminates n a radially offset portion 23 which forms an external annular shoulder 33.

The external diameter of the offset portion 23 is thesame as the diameter of the barrel portion of the body 4, and both these parts are` encased in a sleeve 3l which is clamped to the body 4 by means of a split ring 32 which is contracted by means of an adjusting screw 33.

A compression coil spring 34 is interposed between the shoulder 30 of sleeve 28 and the end of the barrel portion 2 of the body 4. The spring 34 normally biases the sleeve 23 to the left as viewed in Fig. 2.

Both the sleeve 3I and the barrel 2 are provided with a longitudinally extendingV slot as at 35,' this slot being of suflicient width and length to permit reciprocal movement therein of a trigger 3B whichVV is secured, as by brazing, to the sleeve 28. By means of the trigger 36, the sleeve 2B may be manually retracted in opposition to spring 34 thus relieving the jaws 23 of envelopment by the offset portion 23 and permitting them to expand radially.

The butt portion I of the body 4 is provided with a cavity 31 which serves as a reservoir for the hydraulic fluid. The reservoir 31 is closed by a threaded cap or cover 33.

The butt I is provided with a second cavity 33 which serves as a cylinder in which is slidably mounted a piston 40 having a blfurcated end portion forming ears 4 I. A suitably formed handle 42 is pivotally connected to the ears 4I of the piston 43 by means of' a pin 43, this connection being` intermediate the ends of the handle. The lower end 44 of the handle is pivotally secured, as by pin 45, to a link 46, which, in turn, is pivotally secured to the butt I by pin 41. The link 4B is concealed Within the butt in a recess 48 which is large enough to permit free movement of the link.

The piston 40 is provided with a circumferential recess 43 in which is retained a resilient sealing ring 50 which has wiping engagement with the wall of cylinder 33. A compression coil spring terminates in a .shoulder` 5I is disposed between the piston 40 and the end of the cylinder 33 and normally urges the piston to the left as viewed in Fig. 2.

The handle 42 is provided with parallel flanged portions' or wings; 52 which are received in vertical recesses 53 provided in the butt I and thus serve to guide the movement of the handle.

The butt I is further provided with a cavity or valvev by-pass chamber 54 which is counterbored as at 55 to form a valve chamber, and tapped to receive a threaded valve body 56. The vakvebodyyin turn, has a central bore 51 in which is slidably received a valve stem 53 having an enlarged conical end portion 53.

The-.bore51 is counterbored and tapped to receive a resilient sealing ring 33 which is retained in position by a threaded follower 6I.

A portion of the value stem 53 projects exteriorly of the body 4 and has secured thereto an enlarged head or button 62 for convenience in effecting manipulation of the valve.

Asbest seen in Figs. 2 and 4, the valve body 58 is provided with a portion 63 of reduced diameter,y which portion has a plurality of diametrically extending openings 64 provided therein. The valve stem 5B also has a portion E5 of reduced diameter thereby forming a clearance space between the valve stem and the interior wall ofthe portion G3 yof the valve body. The conical end 53 of the valve stem seats on the valve body 56 in sealing engagement with the bore 51.

A channel or passageway 6B interconnects the cylinder I0 with the by-pass chamber 54 and a channel 61 interconnects `the by-pass chamber 54 and the cylinder 33. A third channel B3 interconnects the valve chamber 55 and reservoir 31, and another channel 63 interconnects reservoir 31 -andcylinder 33. The function of these channels will be described hereinafter.

A ball check valve 13 is mounted in the channel 61, intermediate the cylinder 33 and the by-pass chamber `54, and another ball check valve 1I is mounted in the ychannel B3, intermediate the reservoir 31 and -cylinder 33.

The operation of the instrument will now be described.

As heretofore stated, it is necessary that a high pressure be developed by the plunger 5. To attain thisobjective,A the spring I3 must have a high energization value, for example, 25o-300 pounds when fully compressed. It will readily be apparent that in order to cock the plunger, that is, retract it in opposition to the spring I3, a great deal of force or strength would be required. In fact, it would normally be considered an impossibility for the average individual to manually retract the plunger. Therefore, our invention lies in providing means for effecting retraction of the plunger, which means are readily manually operable by the user of the instrument.

With the plunger 6 extended, that is, with the spring I3 expanded, the reservoir 31 is filled with a suitable hydraulic uid such as light mineral oil or the like, so that the cylinder 33 and the channels 31 and 33 are substantially filled. After the reservoir 31 has been completely charged with the hydraulic fluid, the reservoir is closed and sealed by means of the cover 38.

The butt portion I of the device is new grasped in one hand with the fingers overlying the handle 42, which is normally disposed in the dotted line position shown in Fig. 2, due to the urging of piston spring 5I.

`The piston 43 is then reciproca-ted in cylinder 39 by means of the compound pivotal movement of handle 42. The link 46, which permits vertical movement of the handle 42, prevents any lateral strain from being imposed on the piston 40 during pivotal movement of the handle.

As the piston is forced to the right, as viewed in Fig. 2, it forces the uid through ball valve 1I) into channel `61. During this displacement of the fluid, the back pressure in channel 69 causes ball check valve 1I to close, thereby preventing a return flow of the fluid into reservoir 31.

Upon completion of the compression stroke of piston 49, the spring 5I returns the piston to its initial position, and during this movement, the suction or vacuum created in the cylinder 39 causes ball check valve 1I to open, thereby -causing an additional flow of fluid from reservoir 31 through channel 69 into cylinder 39. At the same time, the back pressure in channel 61 causes ball check valve to close, thereby preventing any return ilow of the fluid from channel 61 into cylinder 39.

As this uid pump, of which piston 49 is an element, is operated, the fluid is forced through channel 61, through by-pass chamber 54, through channel Eli and into cylinder III, where it steadily builds up an increasing hydraulic pressure. This pressure, acting on piston II, forces it to the right, as viewed in Fig. 2, thereby retracting the plunger 6 and further extending the rod I5 beyond cap I4.

The fluid pressure also acts on the exposed surface of the conical portion 59 of valve stem 58 thereby urging the valve stem to the left, as viewed in Fig. 2, and causing the bore 51 to be closed against passage of the fluid.

The fluid pumping operation is repeated several times until the spring I9 has been fully compressed. The plunger 6 is thereby in cocked position.

In order to prevent any inadvertent or accidental release of the plunger 6, means are provided to lock the plunger in its fully cocked position, For this purpose a circumferential recess 12 is provided on extension rod I5, which recess is formed at that longitudinal point on the rod where, when cocked, it llrst projects from the cap I4. To the cap is pivotally secured as by screw 13, a locking disc or plate 14, which is best shown in Fig. 5. The plate 14 has a key-hole slot formed therein, which slot has a portion 15 of slightly greater diameter than the recessed portion 12 of rod I5, but of lesser diameter than the large diameter of the rod I5. The slot also has a portion 16 which is larger in diameter than the diameter of rod I5.

Two arcuate depressions 11 are formed in that surface of the locking disc which is contiguous to the cap I4, and a spring-pressed ball 18, which serves as a detent, is mounted in a cavity in the cap I4, and engages the depressions 11 to yieldably retain the disc in one or the other of two positions.

During the pumping action, the locking disc 'I4 is maintained in the dotted line position shown in Fig. 5, thereby permitting free longitudinal movement of the rod I5 through the slotted portion 16 of the disc. However, when the spring I9 has been fully compressed, the locking disc is rotated about screw 13 to the solid line position shown in Fig. 5, in which position, the slot portion 15 embraces the recessed portion 12 of rod I5 and prevents any relative longitudinal movement of the rod.

A longitudinally extending fiat 19 is provided on the projecting threaded portion of the rod I5, and suitable index marks 89 are inscribed on the fiat 19. In the instant case, four index marks are shown in Fig. 2 and each mark represents a plunger movement equivalent to one-eighth cc. of inoculant ejected. Thus, were the released with the adjusting nut I1 being in the position shown, a half cc. of inoculant would be ejected, as will hereinafter more fully appear. Similarly, were the adjusting nut I1 moved to the next adjacent mark 80, the ejecting movement of the plunger 6 would be arrested by abutment of nut I1 against locking disc 14 at a point corresponding to the ejection of cc. of inoculant.

'I'he cartride or capsule which is utilized in connection with the instrument herein described is generally of the permanent or re-usable type and may be of a variety of shapes or sizes. However, the cartridge illustrated in Figs. '1 and 8 of the drawings, exemplifies a type of cartridge which could be satisfactorily used.

Referring more particularly to Fig. '7 of the drawings, the cartridge C comprises a hollow cylindrical shell BI the forward portion of which is conically tapered to a round nose 82 which is pierced by a small aperture B3, this aperture being approximately .003 inch in diameter.

The rearward portion of the shell 8| terminates in a radially outwardly extending circumferential ange 84 which is adapted to be received in the recess 24 in the collet jaws 23.

Slidably mounted in the shell 8| is a piston 35 having a flat rear face 86 and a conical front face 81. The piston is provided with a circumferential recess 8B in which is retained a resilient sealing ring 89 which has wiping engagement with the wall of the shell.

The cartridge C is filled with inoculant by removing the piston 85, and after the piston is replaced, the cartridge is ready for use.

In order to load the cartridge C in the injector instrument, the trigger 38 is retracted, causing the sleeve 29 to slide to the right, as viewed in Fig. 2, in opposition to the spring 34. This retractive movement causes the offset portion 29 of the sleeve to recede from the jaws 23 of the collet 2 I, whose inherent resiliency will cause the jaws to expand and open.

The cartridge C is then inserted in the collet with the flange portion 84 thereof in alignment with the recess 24.

It will be noted that the jaws 23 have an inclined or tapered external surface 99 which is engageable by the end 9| of the offset portion 29 of sleeve 23 when the jaws are expanded.

After the cartridge is inserted, the trigger 36 is released and the spring 34 returns the sleeve 2B to its initial position. This return movement of the sleeve causes the end 9I thereof to ride over the surface 90 and cam the jaws 23 into clamping relationship whereby the cartridge is firmly gripped.

After the nose 82 of the cartridge is properly positioned against the skin of the patient to be inoculated, the locking disc 14 is rotated to the non-locking position shown in dotted outline in Fig. 5, and the plunger 6 is released by depressing the button S2 on valve stem 58.

The opening of the valve permits the hydraulic fluid to be released from the cylinder IU by owing through channel B6 into bore 51 of valve body 5B and thence through openings 64 into valve chamber 55. From chamber 55 the iluid returns 7 to reservoir rlrthreughebannel;sthusrecsteb- Vnshing the supply nf nuidin the reservoir- Although movementfof `the plnngercan bearrestedvby releasing.buttomlttherebv clcsins the valve, it is preferable that the adjusting nut I1 l.be rso,positior1edas to step themovement of the plunger Whenxthedesired amountof noculant .hsben elem/ed.

Thebody of fluid in the cylinder |0 serves t0 cushion thev forward movement of plunger `land therefore, the ejecting action is more sustained endless abrupt than would be the case were the movement entirely mechanical. This is a very desirable feature in- .such an instrument, not only because it permits better control over the jet inoculation process, butalso because it reduces and minimizes the shock and wear and tear on the device itselnas well as onthe cartridge.

It .will be obvious that as the plunger 5 moves forwardly, -it displaces trici-ge C and causes the inoculant to be ejected in a high velocity jet through the opening 83.

`As is apparent from the foregoing description, the cartridge C must Vbe removed from the device faftereach injection and must be refilled and replaced for the succeeding injection. This method of operation is quite satisfactory under circumstances where the instrument is being utilized only occasionally or intermittently, as intreatingpatients singly in a hospital or doctors omce. However, there may be occasions when large groups of people must be inoculated rapidly, such as -cccursin the inoculation of members of the armed forces. Under such circumstances, it is desirable that the time consumed in refilling and reloading the cartridge be minimized or eliminated entirely.

In Figs. 9 to l2 of the drawing. we have shown a modified form of an inoculant injector device which is particularly adapted for repeated or multiple shot operation for the lrapid inoculation 4of large groups of people.

Except as yhereinafter described, the instrument is constructed in accordance with the previously described embodiment shown in Figsl to 18 Ainclusive.

In the modified form of injector device, the piston I I, plunger 5, and extension rod l5 are integrated into a single element having a bore 92 extending longitudinally therethrough. The cxtension rod |5 terminates in a threaded portion 93 of reduced diameter which forms e. shoulder 34 on the 4rod I5.

The rod I5 projects through a cap 9,5 which is threadedly secured to the exterior of the piston housing 3 and which is provided with external screw threads 06. The cap is provided with spanner openings 01 to facilitate its assembly to the housing 3.

An internally threaded adjustable sleeve 90 having a circumferential flange 30 is threadedly secured to the cap 95, this sleeve having a central opening to permit the rod I5 to pass therethrough. The flange 39 is slidably contained within another sleeve |0| which has threadedly secured thereto a disc |02 which in turn is secured to the portion 33 of rod I5 in abutment with the shoulder 04 thereof. The disc |02 is likewise provided with Spanner openings 91.

It will be apparent that as rod I moves to the left, as viewed in Fig. 9, the disc |02 will move into abutment with sleeve 33 and thereby will arrest or limit the movement of rod I5 and plunger 6. By rotating the sleeve 33 in a countercleckwise direction, it is caused to move longithe piston 85 in the car- .s

,tudinaliy rearwardly Acurtail the. stroke .of :stroke of plungerf canbe adjusted Ybyrneans of fthereby vwill vfurther the plunger 0. Thus, the

adjusting sleeve-39. In order that the length of stroke may be predetermined, the cap T has `formed thereon-a longitudinally extending lflat |03 on which maybe inscribed suitable indicia which, when correlated with the positionV of the forward edge of adjusting sleeve 30, will indicate, in terms of `cubic centimeters or fractional parts `of shots, the length of stroke of `the vplunger 6.

To thcportioni'offrod I5 is threadedly secured a syringe'or reservoir body |04 which has an opening |05 in alignment withfthebore'iof rod l5. A resilient Washer |06 Vis interposed between the Vend of rod I5 and body |04-inorder to prevent leakage.

Slidably contained within the body |04=is a piston |01 which is provided with an annular recess |08 adapted to contain a resilient ring '|03 having wiping engagement with the wall of the body |04. The piston is tapped to receive a threaded stem ||0 having a portion of reduced diameter thereby forming a shoulder lf2.

The stem terminates in a threaded portion H3.

The end of the reservoir body |04 is closed' by meansof a cap ||4 which is threadedly secured to the body and which has a central opening I I5 which serves as a bearing for the portion I I I of the stem A knob I I6 is threadedly secured to the portion ||3 of the stem and is utilized to rotate the stem ||0 so as to move the piston |01 axially in one direction or the other. The face of the knob which lies adjacent the cap ||4 is provided with a plurality of circumferentially spaced depressions ||1, four equally spaced depressions being utilized in the embodiment shown. The cap ||4 is provided with a cavity ||0 containing a spring-pressed ball ||3 which is adapted to successively engage the depressions as the knob IIB is rotated. The detent action of the springpressed ball is utilized in a manner which will be described hereinafter.

The plunger B, which extends through the barrel 2 of the instrument, terminates in a threaded portion |20 of reduced diameter, thereby forming a shoulder |2I. On this threaded portion |20 is secured a plunger cap |22 which is shown in detail in Fig. 12.

The plunger cap |22 comprises a body |23 to which is integrated a. resilient tip or nose |24. The body is bored as at |25 and is counterbored and tapped as at |26. A channel |21 leads from the bore |25 to the exterior of the body rearwardly cf the nose |24.

A spring-pressedball |20 is contained in the bore |25, and this ball seats against an opening |20 which is provided in a hollow-head screw |30 which is threadedly secured to the body in bore |20 thereof. A washer |3| and a resilient gasket |32 are interposed between the end ofthe portion |20 of the plunger 6 and the screw |30 in order to prevent leakage.

The body |23 is provided with an annular recess |33 in which is contained aresilient O-ring |34 which has wiping engagement with the 'internal wall of an ampule A of the type ordinarily utilized for inoculants. The ampule has a small opening-|35 at thenose thereof.

9 lnstead of the collet 2| described in the firstmentioned embodiment, we now utilize a selfopening collet |35, the jaws of which have inwardly extending flanges |31 which are adapted -to embrace the forepart of the ampule A and hold it firmly in position. The collet is released by retraction of trigger 36 as hereinbefore described.

On the barrel 2 of the instrument, we have provided a split ring |30 having a slotted ear |39 projecting therefrom. The ring |38 serves the same function as the previously described ring 32, except that it also serves to retain a locking lever |40 which is pivotally secured thereto by means of a pin |4|. A resilient sleeve |42 surrounds the pin I4| and serves to hold the lever in whatever position it is placed.

The lever is so located that its lower portion |43 will lie in the space intermediate the button 62 and the nut 55 so as to prevent the depressing of the valve stem 58, The lever |40 may be rotated clockwise, as viewed in Fig. l1, to release the button 52.

In utilizing the instrument for multiple-shot operation, the reservoir |04 must be lled with the inoculant which is to be injected. This may be accomplished in one of two ways. The reservoir, after removal from the rod l5, may have threadedly secured thereto an adapter (not shown) on which can be mounted a hypodermic needle. By rotation of the knob IIB, the piston |01 is moved to the left, as viewed in Fig. 9, and the needle is then inserted in the bottle containing the liquid. The knob H6 is then counterrotated and the consequent retraction of the piston |01 draws the inoculant into the reservoir body.

In lieu of the foregoing, the reservoir may be lled by pouring the inoculant into the body |04 through an opening |44 which is ordinarily sealed by a threaded plug |45.

After the reservoir has been filled, it is assembled to the rod I5. In order to prevent the rod I5 from rotating during the assembly operation, the rod has two oppositely disposed plane surfaces |46 formed thereon, which surfaces extend longitudinally thereof for a portion of its length. As seen in Fig. l0, the central opening |41 in cap 95 conforms to the shape of the rod |5 and thereby prevents axial rotation thereof.

In order to ll the ampule A with inoculant, the plunger 5 is first retracted by the pumping of handle 42, asheretofore described. The instrument is then pointed upwardly and the knob ||6 is rotated until the inoculant comes out of the opening |35 in the ampule A. In order to prevent the stem ||0 from becoming air-bound in the piston |01, the stem is provided with a bore |48 which serves to vent any entrapped alr.

With the ampule A thus filled, the adjusting sleeve 98 is set to give thedesired stroke of plunger 6, that is, one shot, a half shot, etc.

'I'he locking lever |40 is then rotated to release position, and the button 62 is depressed thereby releasing the plunger 6 and causing the plunger cap |22 to move forwardly in the ampule and eject the inoculant. As the plunger cap reaches the end of its stroke, the nose |24 thereof becomes wedged in the nose of the ampule and seals the opening |35, thus preventing any drip or leakage from the ampule after the shot has been completed.

During the forward movement oi the plunger cap, the back pressure on the fluid in channel |21 and bore |25 causes the ball |28 to seat on the 10 screw |30 and prevents any rearward now of the fluid.

In order to repeat the inoculating shot, the plunger 6 is again retracted by means of manipulation of the handle 42 and the lock lever |40 is rotated to the safety or locking position. The

instrument is again pointed upwards and the knob ||5 is rotated one click (one-fourth revolution), two clicks (one-half revolution). ete., as desired. Inasmuch as the bore 92 is now full of inoculant, the movement of piston |01 causes the ampule A to receive an amount of fluid which corresponds to the volume displaced by the piston. The piston will, of course, move longitudinally an exact distance for each full or fractional revolution of the knob IIB. Therefore the quarterturns of the knob can be correlated to the movement of the piston |01 so as to denote the quantity of inoculant which is going into the ampule. Thus, one click may denote one-eighth cubic centimeter or one-half shot; two clicks, onefourth cc. or a full shot; etc.

Ihe syringe or reservoir |04 may have a capacity of, for example, 20 cc., and if one shot requires V2 cc., it will be apparent that about 40 inoculator shots can be given with the instrument before having to rell it.

Thus it will be apparent that the rapid inoculation of large groups of people is made possible by the self-loading characteristics of our invention.

The instrument may also be used for single shot operation using standard ampules, in which case the syringe assembly is not required as the ampule is replaced after each shot.

The adjusting sleeve 98, which determines the length of stroke of the plunger 6, is utilized primarily for single shot operation. The metering oi' the fluid by means of the knob H6 is used solely for multiple shot operation.

rI'hus we have provided an inoculant injector instrument which in all respects meets the objectives hereinbefore set forth.

It is to be understood that the forms of our invention, herewith shown and described, are to be taken as prefered examples of the same, and that various changes in the shape, size and arrangement of parts may be resorted to, without departing from the spirit of our invention or the scope of the subjoined claims.

Having thus described our invention. We claim:

said piston, a spring engaging said piston and energizable in response to said displacement of said piston, a plunger secured to said piston and movable therewith, an inoculant-charged body disposed in the path of movement of said plunger, and valve means communicating with said cylinder and operable to recirculate the fluid from said cylinder to said pump and release the pressure in said cylinder whereby said plunger is displaced by the action of said spring.

2. A combination, as deilned in claim l, in

is immobilized.

3. A combination, as defined in claim l in which a movable extension rod is secured to said piston, which rod projects exteriorly of said 11 cylinder, and adjustable stop means are provided on said rod for limiting the movement of said rod in response to action of said spring, whereby corresponding movement of said plunger is restricted.

4. In an injector instrument, the combination of a cylinder, a piston slidably mounted in said cylinder, a spring engaging said piston, a plunger secured to said piston and movable therewith, an inoculant-charged body disposed in the path of movement of said plunger, a fluid reservoir provided in said instrument, a pump communicating with said reservoir, said pump being operable to force fluid from said reservoir into said cylinder whereby said piston is retracted in opposition to said spring, and means for selectively releasing said uid from said cylinder and recirculating it to said reservoir whereby said plunger is actuated by said spring.

5. A combination, as defined in claim 4, wherein said means comprise a channel interconnecting said cylinder and said reservoir, and a normally closed valve interposed in said channel.

6. A combination, as defined in claim 4, wherein an extension rod is secured to said piston and movable therewith, which rod extends exteriorly of said cylinder, and adjustable stop means are provided on said rod for limiting the springactuated movement of said rod whereby corresponding movement of said plunger is restricted.

'7. A combination, as defined in claim 6, wherein locking means are provided exteriorly of said cylinder for selectively securing said rod against movement and thereby immobilzing said plunger.

8. In an injector instrument, the combination of a cylinder, a piston slidably mounted in said cylinder, a plunger secured to said piston and movable therewith, an inoculant-charged body disposed in the path of movement of said plunger, spring means engaging said piston. fluid pressureproducing means communicating with said cylinder and adapted to retract said piston in opposition to said spring, manually operable means for actuating said pressure-producing means, whereby said plunger may be retracted, and valve means for selectively releasing the duid from said cylinder and recirculating it to said pressureproducing means, whereby said plunger' is displaced by action of said spring.

9. In an injector instrument, the combination of a cylinder, a plunger movable in said cylinder, an inoculant-charged body supported in alignment with said cylinder, spring means in said cylinder for advancing said plunger into said body to discharge the contents thereof, and fluid pressure means carried by said instrument, including a pump, for forcing fiuid into said cylinder to retract said plunger in opposition to said spring means, whereby said spring means is put under compression.

10. In an injector instrument, the combination of a cylinder, a piston movable in said cylinder, a plunger secured to said piston for movement therewith, an inoculant-charged body supported in alignment With said cylinder, spring means engaging the plunger for advancing said plunger into said body to discharge the contents thereof, and fluid pressure means carried by said instrument, including a pump, for forcing iiuid into said cylinder to retract said piston and plunger in opposition to said spring means, whereby said spring means is put under compression.

l1. In an injector instrument, the combination or a cylinder, a piston movable in said cylinder, a plunger secured to said piston and moveable therewith, an inoculant-charged body supported in alignment with said cylinder, spring means engaging the plunger for advancing said plunger into said body to discharge the contents thereof, iluid pressure means carried by said instrument, including a pump, for forcing fluid under pressure into said cylinder to retract said piston and plunger in opposition to said spring means, whereby said spring means is put under compression, and valve means for selectively recirculating said fluid from said cylinder to said pump.

12. In an injector instrument, the combination of a hollow plunger, means for retracting said plunger, an ampule disposed in axial alignment with said plunger, metering means for feeding a predetermined volume of liquid into said ampule through said plunger, means for advancing said plunger into said ampule to eject the liquid therefrom, and a resilient nose on said plunger, adapted to engage said ampule upon completion of the stroke of said plunger, whereby to seal said ampule against further discharge of liquid.

13. In an injector instrument, the combination of a hollow plunger, means carried by said instrument for retracting said plunger, an ampule supported in alignment with said plunger, a liquid reservoir carried by said instrument communicating with said plunger, a piston movable in said reservoir, rotatable means secured to said piston for advancing said piston a predetermined distance per revolution thereof to feed liquid into said ampule through said plunger, and means forming part of the instrument for advancing said plunger to discharge said liquid from said ampule.

14. A combination, as defined in claim 13, wherein said rotatable means comprises a threaded element engaging said piston.

15. A combination, as defined in claim 14, wherein said threaded element is provided with indicating means for determining the relative angular rotation thereof.

16. In an injector instrument, the combination of a cylinder, a hollow plunger movable in said cylinder, a hollow body adapted to contain inoculant supported in alignment with said plunger, metering means on the instrument associated with said plunger for feeding inoculant into said body through said plunger, spring means engaging the plunger for advancing said plunger into said body to discharge the contents thereof, and fluid pressure means carried by said instrument communicating with said cylinder to retract said plunger in opposition to said spring means, whereby said spring means is compressed.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 411,375 Cooke Sept. 1'7, 1889 1,144,343 Benmosche et al. June 29, 1915 1,569,457 Carstens Jan. l2, 1926 2,047,010 Dickinson July 7, 1936 2,295,849 Kayden Sept. 15, 1942 2,322,245 Lockhart June 22, 1943 2,374,368 Mejia Apr. 24, 1945 2,413,303 Folkman Dec. 31, 1946 2,550,163 Phenning Apr. 24, 1951 FOREIGN PATENTS Number Country Date 102,221 Australia Oct. 7, 1937 505,931 France Aug. 10, 1920 624,958 Great Britain June 20, 1949 

